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Striking semiconductors with light in the furnace could reduce defects
June 17, 2016
Source: ASM International
The University of Utah, Salt Lake City, and the National Renewable Energy Laboratory, Golden, Colo., report that its researchers have discovered that if light is shone on semiconductor alloys as they are fired in a furnace at high temperatures, the light generates extra electrons that could suppress the growth of defects.
Prof. Mike Scarpulla of the University of Utah, and senior scientist Kirstin Alberi of the NREL, have developed a theory that adding light during the manufacturing of semiconductors could reduce defects and potentially make more efficient solar cells or brighter LEDs. The role of light in semiconductor manufacturing may help explain many puzzling differences between processing methods, and may unlock the potential of materials that could not be used previously.
The theory applies to all semiconductors, but is most applicable to compound semiconductors such as gallium arsenide (GaAs), cadmium telluride (CdTe), and gallium nitride (GaN). GaAs is used in microwave radios in cellphones, CdTe in solar panels, and GaN in LED light bulbs.
The fact that compound semiconductors require more than one chemical element makes them susceptible to defects in the material at an atomic scale, says Prof. Scarpulla "Defects produce lots of effects like difficulty in controlling the conductivity of the material, difficulty in being able to turn sunlight into electricity efficiently in the case of solar cells, or difficulty in emitting light efficiently in the case of LEDs."
"We ran simulations of what happens," he says. "If you put a piece of a semiconductor in a furnace in the dark, you would get one set of properties from it. But when you shine light on it in the furnace, it turns out you suppress these more problematic defects. We think it may allow us to get around some tricky problems with certain materials that have prevented their use for decades. The exciting work is in the future though — actually testing these predictions to make better devices."
Prof. Scarpulla and Dr. Alberi reported their findings in a paper titled "Suppression of Compensating Native Defect Formation During Semiconductor Processing Via Excess Carriers," published June 16 in the journal Scientific Reports. The research was funded by grants from the U.S. Department of Energy Office of Basic Energy Sciences.
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